A US federal court has released new video footage showing California prison guards repeatedly spraying mentally ill inmates with pepper spray in an apparent attempt to convince the prisoners to take their medication.

California policy requires officers in the Department of Corrections to film all cell extractions.

The footage in question was played in court in October as part of an inmate’s lawsuit seeking to halt the use of pepper spray against the growing mentally ill prison population.

Perhaps the most disturbing of the six tapes shows a naked screaming inmate at Corcoran State Prison who is sprayed at least five times within 15 minutes.

An officer can be heard saying “spray him again” more than once, with roughly six officers then overwhelming the prisoner and strapping him down to a gurney.

Lawyers representing the roughly 30,000 mentally ill prisoners against excessive force said the very notion of pepper spraying inmates is evidence that the Department of Corrections does not follow a policy meant to help mentally ill inmates - many of whom will be re-released into the public at some point.

“The mentally ill are being punished for their mental illness,” San Francisco attorney Jeffrey Bornstein told the judge.

The US has come under international criticism for violation of prisoners’ rights especially in its controversial Guantanamo Bay center.

Most recently the US officials were grilled by rights groups for force-feeding Guantanamo inmates who were on a long hunger strike to demand their rights.

The US remained defiant on that case as well saying force-feeding the hunger strikers, which is a painful process done with a tube passing through their noses, was essential for their health.